A normal human heart pumping pattern is called a sinus rhythm, and the pattern is regulated by the body's biological pacemaker within the upper right chamber of the heart, which is commonly referred to as the right atrium. This natural pacemaker, which is generally referred to as the sinoatrial (“SA”) node, sends electrical signals to the right and left ventricular muscles in the lower chambers of the heart. The ventricular muscles then implement the pumping action under the control of the SA node. The right ventricular muscle pumps blood to the lungs for oxygenation, and the left ventricular muscle pumps the oxygenated blood to various parts of the body.
In certain circumstances, the normal or sinus heartbeat rhythm may be adversely affected as a result of some type of malfunction in the heart's electrical control system. When this type of malfunction occurs, an irregular heartbeat may result, causing the ventricular muscles to pump ineffectively, thus reducing the amount of blood pumped to the body. This irregular heartbeat is generally referred to as an arrhythmia.
A particularly serious arrhythmia is known as ventricular fibrillation (“VF”), which is a malfunction characterized by rapid, uncoordinated cardiac movements replacing the normal contractions of the ventricular muscles. In this event, the ventricular muscles are not able to pump blood out of the heart, and there is no initiation of a heartbeat. VF rarely terminates spontaneously, and is therefore a leading cause of sudden cardiac arrest. The unpredictability of VF and other irregular heart beat conditions exacerbates the problem, and emphasizes the need for early therapeutic intervention to prevent the loss of life.
Defibrillators are devices for providing life-saving electrical therapy to persons experiencing an irregular heat beat, such as VF. A defibrillator provides an electrical stimulus to the heart in an attempt to convert the irregular heat beat to a normal sinus rhythm. One commonly used type of defibrillator is the external defibrillator, which sends electrical pulses to the patient's heart through external electrodes applied to the patient's chest. External defibrillators may be manually operated (as are typically used in hospitals by medical personnel), semi-automatic, semi-automated, fully automatic, or fully automated devices, where they can be used in any location where an unanticipated need may occur.
In practice, defibrillation pulses are administered to the patient when necessary, and cardio-pulmonary resuscitation (“CPR”) is administered between pulses. CPR includes the delivery of chest compressions to the patient (to stimulate blood flow) and the delivery of ventilations to the patient (to provide air to the lungs). Recent statistical studies suggest that the amount of time devoted to CPR during a typical resuscitation event may be less than optimal in real world situations. Although some of the defibrillator usage time is necessarily occupied by rhythm analysis and defibrillation functions—which in most cases preclude the simultaneous delivery of CPR—there may be an undesirable amount of “wasted” time during which neither the defibrillator device nor the caregiver are actively administering treatment to the patient.
Presently, there are no straightforward and elegant ways to assess the proportion of time that chest compressions and/or ventilations were performed during a resuscitation event. Such assessments can be useful during post-event review of a defibrillator usage case. Currently, caregivers or case reviewers must make educated guesses via laborious evaluation of ECG signal artifacts (which can be highly variable from case to case), captured scene audio (which may not be available for all defibrillator devices), device prompts, and expectations of caregiver behavior.
Accordingly, it is desirable to have a system for providing quantitative post-event feedback related to the amount and proportion of time that chest compressions and/or ventilations were performed during a cardiac arrest response treated by a defibrillator device. In addition, it is desirable to have a system for providing other figures of merit related to the delivery of CPR during a resuscitation event, where such figures of merit are determined from post-event patient data analysis. Furthermore, other desirable features and characteristics of the present invention will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and the foregoing technical field and background.